With the ongoing development of network technologies, a number of computers serving as client terminals are connected to a network. Accordingly, the incidence of software damage inflicted by computer viruses and of malicious client terminal intrusions by hackers and crackers, who seek out and exploit vulnerability of software, is growing. Therefore, adequate security measures have become vitally important for client terminals.
If the number of client terminals is limited to the extent that a network administrator can control them, the network administrator may alert users to the need for security measures, so that security measures can be taken by updating security patches for OSs or by downloading virus pattern files. Especially, regarding download of virus pattern files, a method of taking security measures is known in which when a client terminal is connected to a network, such as Local Area Network (hereinafter referred to as “LAN”), a virus measure file is automatically transmitted to the client terminal, which reduces the labor required of the network administrator (see, for example, Patent Document 1).